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Transition metal nitrides (TMNs) are considered as potential electrode materials for high‐performance energy storage devices. However, the structural instability during the electrochemical reaction process severely hinders their wide application. A general strategy to overcome this obstacle is to fabricate nanocomposite TMNs on the conducting substrate. Herein, the honeycomb‐like CoN‐Ni3N/N‐C nanosheets are in situ grown on a flexible carbon cloth (CC) via a mild solvothermal method with post‐nitrogenizing treatment. As an integrated electrode for the supercapacitor, the optimized CoN‐Ni3N/N‐C/CC achieves remarkable electrochemical performance due to the enhanced intrinsic conductivity and increased concentration of the active sites. In particular, the flexible quasi‐solid‐state asymmetric supercapacitor assembled with CoN‐Ni3N/N‐C/CC cathode and VN/CC anode delivers an excellent energy density of 106 μWh cm−2, maximum power density of 40 mW cm−2, along with an outstanding cycle stability. This study provides a neoteric perspective on construction of high‐performance flexible energy storage devices with novel metallic nitrides. [ABSTRACT FROM AUTHOR]

Li1.2Ni0.13Co0.13Mn0.54O2/Ti3C2Tx (LMR/TC) composite materials have been synthesized through mixing LMR particles with TC nanosheets. SEM result shows that most LMR particles are anchored on the surface of the Ti3C2Tx nanosheets. Such a structure can short the diffusion pathway for both the electron and lithium ions, enhancing electronic and ionic conductivities. Meanwhile, the composite structure keeps much stable during charge/discharge processes, leading to an enhanced cycling performance of the cathode. The LMR/TC (5 wt% Ti3C2Tx) composite electrode delivers an initial discharge capacity of 279.9 mA h g−1 at 0.1 C with coulombic efficiency of 81.8% and the capacity can maintain 248 mA h g−1 after 100 cycles with capacity retention of 85.7%. In contrast, the initial coulombic efficiency and the capacity retention after 100 cycles at same conditions of the pristine LMR electrode are only 67.1% and 67.6%, respectively. The composited cathode also shows an enhanced rate capacity compared to the pristine LMR. [ABSTRACT FROM AUTHOR]

Ultrathin MoS2 nanosheets are promising anode materials for high energy‐density Li‐ion batteries. However, their practical applications suffer from problems of lower capacity and poor cycling performance. In this work, the electrochemical performance of ultrathin MoS2 nanosheets is improved by the synergistic effect of the MoS2 nanosheet structure and cobalt compositing. The morphological characteristics show that the MoS2/Co composite has a more dispersed ultrathin nanosheet structure with a more uniform size distribution. When it is used as an anode material for lithium‐ion batteries, the MoS2/Co composite exhibits excellent lithium storage performance compared with the MoS2. It delivers a much higher initial discharge specific capacity of 1130 mAh g−1 at 100 mA g−1 and still retains 766 mAh g−1 even at 2 A g−1, exhibiting an excellent rate capability. Besides, it also shows a good cycling performance with a slowly capacity increase to 1340 mAh g−1 after 50 cycles at 100 mA g−1. The MoS2/Co composite structure enhances the conductivity of ultrathin MoS2 nanosheets, shortens diffusion path of Li+, and accelerates Li+ and electron transfer, improving the corresponding electrochemical performance. On form: Ultrathin MoS2 nanosheet/Co composite materials are fabricated by using a facile hydrothermal method followed by subsequent ball‐milling treatment with Co particles. The ultrathin nanosheet structure can effectively shorten the diffusion path of Li+ and accelerate reaction kinetics in the electrode material. The embedded cobalt particles can significantly enhance the electrical conductivity as well as accelerate lithium‐ion and electron transfer in the material. Benefiting from the synergistic effect of the ultrathin nanosheet structure and cobalt compositing, MoS2/Co shows an excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Composites of porous Co0.5Zn0.5 zeolitic imidazolate framework (CZ-ZIF)-derived binary Co/ZnO with reduced graphene oxide (RGO) have been prepared by a wet chemical method and carbonization process. CZ-ZIF-derived Co/ZnO microframes with diameter of about 250 nm were dispersed onto the surface of RGO nanosheets. The impedance matching of the composite could be adjusted by controlling the weight ratio of RGO to Co/ZnO microframes. Due to its porous structure, excellent impedance matching, and dielectric loss characteristics, the Co/ZnO/RGO composite exhibited maximum reflection loss (RL) of − 52.2 dB at 10.96 GHz. Coatings with thickness of 2.0 mm to 4.0 mm showed bandwidth of 5.6 GHz (from 8.72 GHz to 14.32 GHz) for RL of − 10 dB (90% absorption). Additionally, the amount of composite added into paraffin matrix was only 8 wt.%, less than for most electromagnetic (EM) wave absorbers in previous reports. Therefore, such Co/ZnO/RGO composites may be promising candidate EM wave absorbing materials. [ABSTRACT FROM AUTHOR]

The role of the counter electrode (CE) in dye-sensitized solar cell (DSSC) is to collect electrons from the external circuit and reduce I to I in the electrolyte. In this paper, the perovskite-phase LaSrCoO (LSCO) nanoparticles were synthesized through a sol-gel method and used as the CE for DSSC. The cell showed a power conversion efficiency ( PCE) of 3.24 %. To further improve the PCE of CE of the LSCO nanoparticles, the nanocomposites of the LSCO nanoparticles with reduced graphene oxide (LSCO@RGO) have been prepared via a simply physical mixing method and served as the efficient CE for DSSC. The LSCO@RGO nanocomposites exhibit excellent electrocatalytic performance for reduction of triiodide, owing to the positive synergetic effect between LSCO nanoparticles and RGO sheets. As a consequence, the DSSC with the LSCO@RGO nanocomposites CE yielded a PCE of 6.32 %, which is observably higher than that of using pristine LSCO CE (3.24 %) or RGO CE (4.54 %) alone, and up to 88 % of the Pt CE (7.18 %). [ABSTRACT FROM AUTHOR]

MoS2 is a promising anode candidate for high-performance lithium-ion batteries (LIBs) due to its unique layered structure and high specific capacity. However, the poor conductivity and unsatisfactory structural stability limit its practical application. Recently, a new class of 2D materials, V4C3-Mxene, has been found to combine metallic conductivity, high structural stability and rich surface chemistries. Herein, a facile method has been developed to fabricate V4C3-MXene/MoS2/C nanohybrids. Ultrasmall and few-layered MoS2 nanosheets are uniformly anchored on the surface of V4C3-MXene with a thin carbon-coating layer. The ultrasmall and few-layered MoS2 nanosheets can enlarge the specific areas, reduce the diffusion distance of lithium ions, and accelerate the transfer of charge carriers. As a supporting substrate, V4C3-MXene endows the nanohybrid with high electrical conductivity, strong structural stability, and fast reaction kinetics. Moreover, the carbon-coating layer can further enhance the electrical conductivity and structural stability of the hybrid material. Benefiting from these advantages, the V4C3-MXene/MoS2/C electrode shows an excellent cycling stability with a high reversible capability of 622.6 mA h g-1 at 1 A g-1 after 450 cycles, and a superior rate capability of 500.0 mA h g-1 at 10 A g-1. Thus, the V4C3-MXene/MoS2/C nanohybrid could become a promising anode material for high rate LIBs.

The hierarchical porous structure with phosphorus-doped Ni(OH) 2 (P-Ni(OH) 2 ) rods as the core and MnO 2 nanosheets as the shell is fabricated directly by growth on a three-dimensional (3D) flexible Ni foam (NF) via a two-step hydrothermal process. As a binder-free electrode material, this unique hybrid structure exhibits excellent electrochemical properties, including an ultrahigh areal capacitance of 5.75 F cm -2 at a current density of 2 mA cm -2 and great cyclic stability without capacitance loss at a current density of 20 mA cm -2 after 10 000 cycles. Moreover, an all-solid-state asymmetric supercapacitor (AAS) based on a P-Ni(OH) 2 @MnO 2 hybrid structure on Ni foam as the cathode and activated carbon (AC) as the anode is successfully assembled to enhance value the electrochemical properties. The AAS device also shows excellent electrochemical properties including a large potential window of 0∼1.6 V, an areal capacitance is 911.3 mF cm -2 at a current density of 1 mA cm -2 and long-term cycling performance. Meanwhile, the AAS device also delivers a high energy density of 0.324 mW h cm -2 at a power density of 0.8 mW cm -2 ; and can easily light colorful light-emitting diode (LED) lights, suggesting that 3D P-Ni(OH) 2 @MnO 2 hybrid composite has promising potential for practical use in high-performance supercapacitors.